The color filter can attenuate the light intensity, change the spectral composition or limit the optical parts of the vibration surface. One of the common characteristics of filters is that no filter can make the image of celestial bodies brighter, because all filters will absorb certain wavelengths and make objects darker.
The filter is made of plastic or glass and special dye. The red filter can only let the red light pass through, and so on. The refractive index of the glass sheet is almost the same as that of air. All colored light can pass through, so it is transparent. However, after dyeing with dye, the molecular structure changes, the refractive index also changes, and the passing of some colored light changes. For example, when a beam of white light passes through a blue filter, it emits a beam of blue light, while the green light and red light are very few, and most of them are absorbed by the filter.
If the filtering wavelength of the filter is 520nm, the absorption of the 520nm wavelength light is large, and the absorption of the 520nm wavelength light decreases with the increase or decrease of the wavelength, which depends on the half wave width of the filter. If the half wave width of the filter is more than twice, the light will not be absorbed and can pass through completely.
Function of filter:
The filter is very important. It is widely used in photography. Why is the main scene always so prominent in landscape paintings taken by some master photographers? How is it done? That's where the filters are used. For example, if you want to start shooting a yellow flower with a camera and the background is blue sky and green leaves, you can't highlight the theme of "yellow flower" if you shoot it as usual, because the image of yellow flower is not prominent enough.
However, if you put a yellow filter in front of the lens to block the green light from some green leaves and blue light from the blue sky, and let a large number of yellow light from yellow flowers pass through, yellow flowers will be very obvious, highlighting the theme of "yellow flowers".